Torque wrench



Oct. 9, 1956 Filed July 20, 1953 H. C. PEDERSEN ET AL TORQUE WRENCH 4Sheets-Sheet X 20 Oct. 9, 1956 H. c. PEDERSEN ET AL 2,765,890

TORQUE WRENCH Filed July 20, 1955 4'SheetsSheet 2 ATTO F Get. 9, 1956 H.c. PEDERSEN tr AL TORQUE WRENCH Filed July 20, 1953' 4 Sheets-Sheet 3Oct. 9, 1956 H- c. PEDERSEN ET AL TORQUE WRENCH 4 Sheets-Sheet 4 FiledJuly 20, 1953 IN V EN TOR-5 Fiat k6?! TORQUE N CH Application July 20,1953, Serial No. 369,155: 16 Claims. (Cl. 1925'6) Pedersen, Lake Orion,

This invention relates to a torque wrench for rapidly running andtightening bolts and nuts with a predetermined amount of torque beingapplied and more particularly relates to a motor driven nut, screw, andstud running torque wrench which is inherently capable of permitting theoperator to adjust the desired amount of torque desired to be applied tothe nut, screw, or stud by adjusting the amount of torsion loaded intothe torsion spring so that when the amount of torque applied to the nutequals the amount of torsion previously loaded into the spring, thespring anchors move whereby cam means are operated to separate the jawclutches thereby discon- -ecting the motor drive from the driven nut,screw, or stud.

The utility and economy of motor driven torque wrenches are wellestablished as these wrenches save the operator much valuable time andrender his work easier so that not only can he tighten more nuts per daybut also he can work longer hours before encountering muscular fatiguein his hands and arms. The utility of the motor driven torque wrench isoccasioned by the fact that the wrench automatically disconnects fromthe drive when the desired amount of torque is imparted to the nut beingdriven thereby incorporating in the wrench itself the attributes of atorque gauge and thereby eliminating the necessity for testing the driveon each nut or spot checking with a gauge. With the instant motor driventorque wrench the operator merely places the wrench on the nut andallows the motor drive to impart the necessary turning to the nutwhereupon when the motor overruns, he takes the wrench off the nut anddrives the next nut in like manner. In other words, an operator can runnuts on bolts with a known desired torque as fast as he can load thenuts and move the wrench from bolt-to-bolt as the nut running timeconsumed is very small due to the speed of the device.

It is pertinent to here note that a great many torque wrenches andmiscellaneous powered devices have been developed and patented forrunning nuts with a certain amount of torque and it is important to notethat the several devices of the prior art do not fulfill all the demandsrequired of them in that they become inaccurate in the torque appliedand are subject to many breakdowns and failures whereby the use of thedevice is lost over long periods of time and in some instances thetorque wrenches require more time to repair than they are available forrunning.

With the foregoing in view, the primary object of the invention is toprovide a power driven torque wrench which is simple in design andconstruction, inexpensive to manufacture, easy to use, and whicheliminates the necessity of constant repair due to the unique coactionof the various parts and which, if repairs are required, is easy andconducive to quick and complete repair.

An object of the invention is to provide a motor driven torque wrenchhaving a torsion spring which carries the desired amount of torsion ortorque desired to be imparted to the nuts to be run and tightened.

An object of the invention is to provide simple means" for adjusting theamount of torsion in the spring to any desired requirement.

An object of the invention is to provide jaw clutches for connecting anddisconnecting the drive portion from the nut running portion.

An object of the invention is to provide cam means to disconnect the jawclutches when the amount of torsion pre-set in the spring is equal inthe amount of torsion or torque applied to the nut.

An object of the invention is to provide a ball lock to hold the upperjaw clutch out of engagement during the non-engageable neutral positionsuch as during the period when moving the wrench from nut-to-nut.

An object of the invention is to provide an outer sleeve for attachingthe wrench to a motor.

An object of the invention is to provide a sleeve telescoped with andaxially slidable relative to the outer sleeve so as to move the upperjaw clutch from a non-engageable neutral position to an engageableneutral position when moved in one axial direction.

An object of the invention is to provide an inner sleeve telescopedwithin and axially slidable within the outer sleeve so as to engage thejaw clutches when moved in the opposite direction as set forth in thepreceding object.

An object of the invention is to provide an axial abutting relationshipbetween the primary drive shaft and the final drive shaft so that axialthrust imposed on either member is directly transferred to the othermember thereby eliminating the transfer of axial thrust throughassociated members.

These and other objects of the invention will become apparent byreference to the following description of a motor driven spring loadedcam operated torque wrench embodying the invention taken in connectionwith the accompanying drawings, in which:

Fig. l is a longitudinal cross-sectional view of the inventive wrenchshowing all the elements in the drive position; 4

Fig. 2 is a view similar to Fig. 1 showing the component parts innonengageable neutral condition;

Fig. 3 is a view similar to Fig. 1 and 2 showing the component parts inengageable neutral condition;

Fig. 4 is a cross-sectional view of Fig. 1 taken on the line 44 thereof;

Fig. 5 is a cross-sectional view of Fig. 1 taken on the line 5-5thereof;

Fig. 6 is a cross-sectional view of Fig. 1 taken on the line 6-6thereof.

Fig. 7 is a perspective view of the cams and cam carrier;

Fig. 8 is a perspective View of the top portion of the final drive shaftshowing the arms; and

Fig. 9 is a perspective view, partly in cross-section, of the primarydrive shaft and ball-lock assembly.

Referring now to the drawings wherein like numerals refer to like andcorresponding parts throughout the several views, the torque wrenchembodiment disclosed therein to illustrate the invention comprises anouter sleeve 20 having an internally threaded reinforcement 21 weldedthereto which is threaded on the motor housing 22 in fixed axialrelationship. The motor armature drive shaft 23 extends beyond thehousing 22 and the wrench primary drive shaft 24 is threaded thereon. Atthis point it is important to note that the motor housing 22 and themotor armature drive shaft 23 are fixedly connected relative to theouter sleeve 20 and the stub shaft 24 respectively so that the wrenchouter sleeve 24) and primary drive shaft 24 are fixed against axialmovement relative to the motor.

The inner sleeve 25 is axially slidably telescoped within the outersleeve 20 and carries pins 26 disposed in the sic-ts 27 of the outersleeve whereby axial movement of the inner sleeve is limited relative tothe outer sleeve by the radially outer ends of the pins and it is to benoted that the radially inner ends 26A of the pins 26 project radiallyinwardly of the inner sleeve 25, the purpose of which will behereinafter explained.

The inner sleeve 25 carries an upper internal ring 28 and a lowerinternal ring 29 against which are positioned the annular bearings 30and 31 respectively. The driven clutch element or upper spring boss 32is equipped with an annular shoulder 33 riding on the bearing 3%) andalso carries a ring 34 located below the bearing 30 so that the upperclutch element-spring boss 32 is not only rotatably positioned but alsoaxially fixedly located relative to the inner sleeve 25. The lowerspring boss 35 is equipped with a shoulder 36 which engages one side ofthe annular bearing 31 and carries a ring 37 engaging the other side ofthe hearing so that the lower spring boss 35 is not only rotatablypositioned but also axially fixedly disposed relative to the innersleeve 25.

The spring bosses 32 and 35 are equipped with bores which house thefinal drive shaft 38 and are equipped with radial channels 39 and 40which receive the upper tab 41 and lower tab 42 of the torsion spring 43which lies concentric to the secondary drive shaft 38 within the innersleeve 25.

The upper spring boss-clutch element 32 is provided with internal dogs44 (Fig. 6) and the final drive shaft 33 is provided with arms 45 in thearea of the dogs 44 so as to engage the dogs 44 in angular movement asseen in Fig. 6 for holding the upper end of the spring 43 relative tothe lower end of the spring 43 via the final drive shaft 38. Moreparticularly in this connection, the desired amount of preloaded torqueis imparted to the spring 43 by holding the element 32 or the secondarydrive shaft 38 and turning the lower spring boss 35 to wind the springso that the force travels from the lower spring boss 35 through thespring 43 through the upper spring boss 32 to the upper spring boss dogs44 at which point it is transferred back to the final drive shaft 38 viathe arms 45 thereon which abut the spring boss dogs 44. When the desiredamount of wind or torque is loaded in the spring 43, the set-screw 46 istightened against the shaft 38 thereby holding the assembly in thedesired torque-wise preloaded condition. The upper spring bossclutchelement 32 carries the lower jaw clutch teeth 47 and it is now to beparticularly noted that the upper spring boss-clutch element 32, andlower spring boss 35, and all the parts associated therewith are axiallyfixedly located relative to the inner sleeve 25 and move axiallytherewith at all times.

Referring now to Figs. 1 and 6, the dogs 44 occupy approximately onethird of the area of the upper spring boss internal annular opening. Thefinal drive shaft arms 45 occupy approximately a third of this openingand paired cams 43 are disposed between the disassociated sides of therespective dogs 44 and arms 45 and that the paired cams 48 are attachedto the annular cam carrier 49, and, it is to be noted that the camcarrier 49 as seen in Fig. 1 lies within the tooth 47 area whereas inFig. 2 illustrating the earns 47 in their activating position, that thecam carrier 49 is elevated well above the teeth 47 area. It is also tobe noted that primary drive shaft 24 and the final drive shaft 38 abuteach other in the driving relationship so that axial thrust imposed oneither shaft is directly transferred to the other shaft.

Keeping in mind that the first described outer sleeve 20 and primarydrive shaft 24 are axially fixedly connected to the motor and that thenext previously described inner sleeve 25 and its associated parts areinterconnected for axial movement as a unit relative to the outer sleeve20 and associated parts, it is now to be understood that the upperjaw-clutch collar 50 surrounds the primary drive shaft 24 and is capableof relative axial movement not only to the outer sleeve 20 andassociated parts but also relative to the inner sleeve 25 and associatedparts and that the primary drive shaft 24 is equipped with a slot 51which receives the end of the key 52 carried by the collar 50 limitingthe axial movement of the collar 50 relative to the primary drive shaft24 and outer sleeve 20 and that the primary drive shaft 24 is equippedwith a key slot 53 and that the clutch collar 54 is equipped with amating hey slot 54 and that the ball key 55 lies in. both slots 53 and54 keying the primary drive shaft 24- and the clutch collar 59 forrotation together and permitting axial movement of the clutch collar Strelative to the primary drive shaft 24. The primary drive shaft 24 isequipped with a reduced pilot portion 56 which is surrounded by theconical ball loch assembly 57 which coacts with the conical lowerinterior face 53 of the clutch collar 55 The spring 59 chambered in thecavity es of the primary drive shaft 24 bears against the conical balllock assembly 57 urging the balls 61 into locking engagement between theclutch collar conical face 53 and the primary drive shaft pilot portion56 locking the clutch collar 5% relative to the primary drive shaft 24,and the primary drive shaft 24 is equipped with a radial channel whichhouses the spring pressed plungers 62 which bear against the clutchcollar 50 for frictionally holding the clutch collar 50 in an elevatedposition as seen in Fig. 3. Since the hall lock is operable to lock theclutch collar only against upward movement relative to the primary driveshaft 24, the clutch collar 54) is equipped with teeth 63 which areadapted to drivingiy engage the teeth 47 on the upper spring boss-clutchelement 32.

In operation, the device is shown in the nut running and drivingrelationship in Fig. l where the drive is transmitted from the motorarmature drive shaft 23 to the nut 64 via the primary drive shaft 24,balls 55, clutch collar 50, upper spring boss-clutch element 32, spring43, the lower spring boss 35, the final drive shaft 38, and the adaptor65 to drive the nut 64 on to the bolt 66. It is to be understood thatwhen the preloaded torsion of the spring 43 is overcome by the nut 64contacting the base 67 with sufficient force that the secondary driveshaft 38 tends to stop relative to the upper spring boss-clutch element32, the upper spring boss 32 further torsions the spring 43 so as tomove the dogs 44 relative to the arms 45 so that the earns 48 are forcedby the dogs 44 into engagement with the arms 45 causing the carrier 49to rise from the position shown in Fig. l to the position shown in Fig.2, during which movement the carrier 49 first contacts the bottom of thespring lock assembly 57 mov ing the ball 61 out of locking engagementbetween the pilot 56 and the cone 58, leaving the clutch collar 59 freeto move axially upwardly as seen in the figures, and, upon furthermovement of the cam carrier 49 the cam carrier 49 engages the bottomportion of the clutch collar 50 elevating it from the position seen inFig. 1 to the position seen in Fig. 2, which movement disengages theteeth 63 on the clutch collar 50 from the teeth 47 on the upper springboss clutch element 32 allowing the motor drive to overrun the finaldrive shaft 38 and associated parts, thereby disconnecting the drivefrom the nut and leaving the device in non-engageable neutral condition.

When this occurs the operator knows that the nut has been driven withthe preloaded force. The device is now in the non-engageable neutralcondition illustrated in Fig. 2 with the clutch teeth disassociated withthe friction plunger-s 62 holding the clutch collar 50 in the elevatedposition on the stub shaft 24.

The operator now lifts the device by the motor and when this occurs themotor and parts fixed thereto, namely the outer sleeve 20 and stub shaft24 move initially upwardly relative to the inner sleeve 25 so that theinner ends 26a of the pins 26 stand still during the first portion ofthe movement when the stub shaft 24 moves upward-1y with the motor andas the clutch collar 50 is in the position of Fig. 2 at this time, thepins 26 contact the top of the clutch collar 50 and hold the clutchcollar 50 down as the primary drive shaft 24 moves up relocating theclutch collar 50 on the primary drive shaft 24as seen in Fig. 3 but at arelative position above the spring boss-clutch element teeth 47 anddisengaged therewith, and, it is to be noted that the pins 26 limit theupward movement of the outer sleeve relative to the inner sleeve so thatwhen the primary drive shaft 24 moves upwardly via the motor, the pins26A hold the clutch collar 50 downwardly so as to properly relocate theclutch collar on the primary drive shaft for again engaging the teethwhen the sleeve 25 moves into the sleeve 20. The clutch collar 50 isthen in the position seen in Fig. 3 and is locked in this position bythe balls 61 being jammed between the conical face 58 and the pilot 56so that the clutch collar 50 is locked against upward movement until theball lock assembly 57 is first moved up elevating the balls 61 out ofjamming relationship as previously described.

The operator now places the adaptor 65 on the next nut to be run, Fig.3, and drops the weight of the motor thereon which is resisted by theassociated parts so that the inner sleeve 25 and the upper springboss-clutch element 32 and the teeth 47 are axially stationary when themotor moves axially downwardly moving the primary drive shaft 24 andclutch collar 50 locked thereon downwardly so as to engage the clutchcollar teeth 63 with the spring boss-clutch element teeth 47 as seen inFig. l whereupon the engagement of the teeth 63 with the teeth 47 againrotates the final drive shaft 38 via the spring 43 to run the nut nowengaged in the same manner as previously described relative to thepreviously run nut and it is to be noted that the primary drive shaftpilot portion 56 rests directly on the final drive shaft 38 not onlytransferring the incident axial thrust but also spacing the ball lockmechanism 57 above the cam carrier 49 thereby preventing its release sothat the clutch element 50 is locked against upward movement therebyforcing the teeth 47 and 63 into engagement until the cams 48 raise thecarrier 49 to release the ball lock mechanism 57.

The description of the movement of the various parts relative to oneanother must be considered in view of the phase or condition of thedevice at the time. While one part may be described as moving in oneaxial direction, it must be recognized that the other part or parts maybe moving in the opposite direction thereby effecting the relativemovement and such variations are considered within the scope of theinvention.

Although but a single embodiment of the invention has been shown anddescribed in detail, it is obvious that many changes may be made in thesize, shape, detail, and arrangement of the various elements of theinvention within the scope of the appended claims. For example, thetelescoping of the sleeves can be reversed or equivalent mechanicalmeans substituted for the sleeves themselves; the driving and drivenclutches can be reversed so that the driving element includes thetorsion spring; on various types of cams, lock mechanisms and clutchescan be employed within the purview of the invention.

We claim:

1. A limited torque imparting device comprising a driving first clutchelement, a driven second clutch element adapted to be rotated by saidfirst clutch element, said clutch elements being adapted to be engagedand disengaged; cam means adapted to disengage said clutch elements; afinal drive shaft, a spring boss on said final drive shaft, a torsionspring connected at one of its ends to said spring boss at one endthereof, a dog on said second clutch element, an arm on said shaftadapted to abut said dog, said spring being connected at its other endto said second clutch element, said arm on said shaft being adapted toabut said dog on said second clutch element to hold said second clutchelement against rotational movement on said shaft to permit preloadingsaid spring with the desired amount of torque by turning said springboss on said shaft and then securing said boss relative to said shaft;said arm being adapted to abut said dog until the preloaded torque ofthe spring is exceeded by resistance on said shaft and to then move awayfrom said dog to operate said cam means to disengage said clutchelements.

2. A limited torque imparting device comprising a driving spring boss, adog on said spring boss, a final drive shaft journaled in saidspring'boss, an arm on said shaft adapted to abut said dog to furnish areaction point between said shaft and driving boss in an angulardirection opposite to the direction of drive, a driven spring boss fixedon said shaft, a torsion spring having one of its ends connected to saiddriving spring boss and its other end connected to said driven springboss and torque-wise preloaded against the drive direction of saiddriving spring boss so as to urge said arm against said dog at thereaction point so that said spring transmits the drive, and a camdisposed between said dog and said arm operable to disconnect the powerfrom said driving spring boss when the preloaded torque of said springis exceeded by causing said arm to move off said dog against said cam.

3. A three position clutch drive including a nonengageable neutralposition, an engageable neutral position, and a driving position,comprising an axially fixed primary drive shaft, a first axially fixedsleeve surrounding said primary drive shaft in spaced relation thereto,a second axially movable sleeve telescoping with said first sleeve, adriven clutch portion disposed in said second sleeve adapted to moveaxially therewith, a driving clutch portion drivingly keyed to saidprimary drive shaft adapted to move axially in relation thereto andrelative to said second sleeve, said non-engageable neutral positionbeing achieved when said driving clutchelement is axially retractedrelative to said primary drive shaft, said engageable neutral positionbeing achieved when said second sleeve is located axially outwardly ofsaid first sleeve and said driving clutch element is axially extendedrelative to said primary drive shaft; and said driving position beingachieved when said driving clutch element is axially extended relativeto said shaft and said second sleeve is advanced axially into said firstsleeve.

4. A three position clutch drive including a nonengageable neutralposition, an engageable neutral position, and a driving positioncomprising an axially'fixed primary drive shaft, a first axially fixedsleeve surrounding said primary drive shaft in spaced relation thereto,a a second axially movable sleeve telescoping with said first sleeve, adriven clutch portion bearinged in said second sleeve adapted to moveaxially therewith, a driving clutch portion drivingly keyed to saidprimary drive shaft adapted to move axially in relation thereto andrelative to said second sleeve, said non-engageable neutral positionbeing achieved when said driving clutch element is axially retractedrelative to said primary drive shaft; said engageable neutral positionbeing achieved when said second sleeve is located axially outwardly ofsaid first sleeve and said driving clutch element is axially extendedrelative to said primary drive shaft; and said driving position beingachieved when said driving clutch element is axially extended relativeto said shaft and said second sleeve is advanced axially into said firstsleeve; an internal H conical face on said driving clutch portion apilot extensaid pilot non-retractably locking said first clutch elementrelative to said shaft in its extended position; said ball lock bodybeing movable to allow axial retraction of said clutch element.

5. A clutch position lock and torque sensative release combinationcomprising an axially relatively fixed primary drive shaft, an axiallyextending pilot portion on said drive shaft, a driving clutch portionaxially movably disposed on said drive shaft and slidably keyed thereto7 a for rotation therewith having an internal conical face in the areaof said drive shaft pilot portion, a ball lock body having at least onelocking ball disposed between said shaft pilot portion and said drivingclutch portion, a spring urging said lock body balls into lockingengagement with said clutch portion conical face and said portion so asto lock said clutch portion against movement up said shaft until saidbody first is moved in that direc tion out of locked condition, anaxially movable part adapted to contact said lock body under certainconditions of torque to move said lock body out of plunger wedgingrelationship to release drive, and torque sensative means adapted tourge said part against said lock body to release drive when apredetermined amount of torque is developed.

6. A clutch position releasable lock and torque sensative releasecombination comprising a drive shaft, a lock body having plungerssurrounding a portion of said shaft, a clutch portion keyed to saidshaft for rotation therewith and axial movement relative thereto havinga conical face portion in the area of said lock body adapted to wedgethe plungers of said lock body between itself and said shaft, a springurging said lock body into plunger wedging relationship to said face andsaid shaft so that said lock body is releasable for axial movement bythrust in one direction and said clutch portion is releasable for axialmovement by thrust in the opposite direction, an axially movable partadapted to contact said lock body under certain conditions of torque tomove said lock body out of plunger wedging relationship to releasedrive, and torque sensative means adapted to urge said part against saidlock body to release drive when a predetermined amount of torque isdeveloped.

7. A clutch position releasable lock and torque sensative releasecombination comprising a drive shaft, a lock body having plungerssurrounding a portion of said shaft, a clutch portion keyed to saidshaft for rotation therewith and relative axial movement relativethereto having a conical face portion in the area of said lock bodyadapted to wedge the plungers of said lock body between itself and saidshaft, a spring urging said lock body into plunger wedging relationshipto said face and said shaft so that said lock body is releasable foraxial movement by thrust in one direction and said clutch portion isreleasable for axial movement by thrust in the opposite direction, andfriction elements disposed between said clutch element and said shaftpreventing accidental movement of said clutch element in the directionof lock release, an axially movable part adapted to contact said lockbody under certain conditions of torque to move said lock body out ofplunger wedging relationship to release drive, and torque sensativemeans adapted to urge said part against said lock body to release drivewhen a predetermined amount of torque is developed.

8. A limited torque imparting device comprising a driving spring boss,9. dog on said spring boss, 21 final drive shaft journaled in saidspring boss, an arm on said shaft adapted to abut said dog to furnish areaction point between said shaft and driving boss in an angulardirection opposite to the direction of drive, a driven spring boss fixedon said shaft, a torsion spring having one of its ends connected to saiddriving spring boss and its other end connected to said driven springboss and torquewise preloaded against the drive direction of saiddriving spring boss so as to urge said arm against said dog at thereaction point so that said spring transmits the drive, a cam disposedbetween said dog and said arm adapted to be activated to disconnect thepower from said driving spring boss when the preloaded torque of saidspring is exceeded causing said arm to move off said dog against saidcam, a clutch position lock comprising an axially relatively fixedprimary drive shaft, an axially extending pilot portion on said primarydrive shaft, a driving clutch portion axially movably disposed on saidprimary drive shaft and slidably keyed thereto for rotation therewithhaving an internal conical face in the area of said primary drive shaftpilot portion, a ball lock body having at least one locking balldisposed between said shaft pilot portion and said driving clutchportion, and a spring urging said lock body balls into lockingengagement with said clutch portion conical face and said portion so asto lock said clutch portion against movement up said primary shaft untilsaid body first is moved in that direction out of locked condition.

9 A limited torque imparting device comprising a driving spring boss, adog on said spring boss, a final drive shaft journaled in said springboss, an arm on said shaft adapted to abut said dog to furnish areaction point between said shaft and driving boss in an angulardirection opposite to the direction of drive, a driven spring boss fixedon said shaft, a torsion spring having one of its ends connected to saiddriving spring boss and its other end connected to said driven springboss and torque-wise preloaded against the drive direction of saiddriving spring boss so as to urge said arm against said dog at thereaction point so that said spring transmits the drive, a cam disposedbetween said dog and said arm adapted to be activated to disconnect thepower from said driving spring boss when the preloaded torque of saidspring is exceeded causing said arm to move off said dog against saidcam, a clutch position releasable lock, a stub shaft, a lock body havingplunger-s surrounding a portion of said stub shaft, a clutch portionkeyed to said stub shaft for retation therewith and axial movementrelative thereto having a conical face portion in the area of said lockbody adapted to wedge the plungers of said lock body between itself andsaid stub shaft, and a spring urging said lock body into plunger wedgingrelationship to said face and said stub shaft so that said lock body isreleasable for axial movement by thrust in one direction and said clutchportion is releasable for axial movement by thrust in the oppositedirection.

10. A three position clutch drive including a non-engageable neutralposition, an engageable neutral position, and a driving positioncomprising an axially fixed primary drive shaft, a first axially fixedsleeve surrounding said primary drive shaft in spaced relation thereto,a second axially movable sleeve telescoping with said first sleeve, adriven clutch portion disposed in said second sleeve adapted to moveaxially therewith, a driving clutch portion drivingly keyed to saidprimary drive shaft adapted to move axially in relation thereto andrelative to said second sleeve, said non-engageable neutral positionbeing achieved when said driving clutch element is axially retractedrelative to said primary drive shaft; said engageable neutral positionbeing achieved when said second sleeve is located axially outwardly ofsaid first sleeve and said driving clutch element is axially extendedrelative to said primary drive shaft; and said driving position beingachieved when said driving clutch element is axially extended relativeto said shaft and said second sleeve is advanced axially into said firstsleeve, a driving spring boss within said first sleeve, 9. dog on saidspring boss, at final drive shaft journaled in said spring boss, an

arm on said shaft adapted to abut said dog to furnish a' reaction pointbetween said shaft and driving boss in an angular direction opposite tothe direction of drive, a driven spring boss fixed on said shaft, atorsion spring having one of its ends connected to said driving springboss and its other end connected to said driven spring boss andtorque-wise preloaded against the drive direction of said driving springboss so as to urge said arm against said dog at the reaction point sothat said spring transmits the drive and a cam disposed between said dogand said arm adapted to be activated to disconnect the power from saiddriving spring boss when the preloaded torque of said spring is exceededcausing said arm to move off said dog against said cam.

11. A limited torque imparting device comprising a driving spring boss,:1 dog on said spring boss, at final drive shaft journaled in saidspring boss, an arm on said shaft adapted to abut said dog to furnish areaction point between said shaft and driving boss in an angulardirection opposite to the direction of drive, a driven spring boss fixedon said shaft, a torsion spring having one of its ends connected to saiddriving spring boss and its other end connected to said driven springboss and torque-wise preloaded against the drive direction of saiddriving spring boss so as to urge said arm against said dog at thereaction point, a cam disposed between said dog and said arm adapted tobe activated to disconnect the power from said driving spring boss whenthe preloaded torque of said spring is exceeded causing said arm to moveoff said dog against said cam, driving means for said final drive shaftcomprising a primary drive shaft, a lock body having plungerssurrounding a portion of said primary shaft, a clutch portion keyed tosaid shaft for rotation therewith and relative axial movement relativethereto having a conical face portion in the area of said lock bodyadapted to wedge the plungers of said lock body between itself and saidshaft, and a spring urging said lock body into plunger wedgingrelationship to said face and said shaft so that said lock body isreleasable for axial movement by thrust in one direction and said clutchportion is releasable for axial movement by thrust in the oppositedirection, and friction elements disposed between said clutch elementand said shaft preventing accidental movement of said clutch element inthe direction of lock release.

12. A limited torque imparting device constituting a driving clutchelement, a driven clutch element; at least one said clutch element beingadapted to be moved out of engagement relative to said other clutchelement; a torque-wise preloaded final drive spring connected to onesaid clutch element adapted to relatively immovably drive until itspreloaded condition is exceeded and then to move relatively to saidclutch elements, a cam adapted to be activated to disengage said clutchelements by said springs relative movement, a three position clutchdrive including a non-engageable neutral position, an engageable neutralposition, and a driving position comprising an axially fixed primarydrive shaft, a first axially fixed sleeve surrounding said primary driveshaft in spaced relation thereto, a second axially movable sleevetelescoping with said first sleeve, a driven clutch portion disposed insaid second sleeve adapted to move axially therewith, a driving clutchportion drivingly keyed to said primary drive shaft adapted to moveaxially in relation thereto and relative to said second sleeve, saidnon-engageable neutral position being achieved when said driving clutchelement is axially retracted relative to said primary drive shaft; saidengageable neutral position being achieved when said second sleeve islocated axially outwardly of said first sleeve and said driving clutchelement is axially extended relative to said primary drive shaft; andsaid driving position being achieved when said driving clutch element isaxially extended relative to said shaft and said second sleeve isadvanced axially into said first sleeve.

13. A limited torque imparting device comprising a driving clutchelement, a driven clutch element; at least one said clutch element beingadapted to be moved out of engagement relative to said other clutchelement; a torque-wise preloaded final drive spring connected to onesaid clutch element adapted to relatively immovably drive until itspreloaded condition is exceeded and then to move relatively to saidclutch elements, and a cam adapted to be activated to disengage saidclutch elements by said springs relative movement, a three positionclutch drive including a non-engageable neutral position, an engageableneutral position, and a driving position comprising an axially fixedprimary drive shaft, a first axially fixed sleeve surrounding saidprimary drive shaft in spaced relation thereto, a second axially movablesleeve telescoping with said first sleeve, a driven clutch portionbearinged in said second sleeve adapted to move axially therewith, adriving clutch portion drivingly keyed to said primary drive shaftadapted to move axially in relation thereto and relative to said secondsleeve, said nonengageable neutral position being achieved when saiddriving clutch element is axially retracted relative to said primarydrive shaft; said engageable neutral position being achieved when saidsecond sleeve is located axially outwardly of said first sleeve and saiddriving clutch element is axially extended relative to said primarydrive shaft; and said driving position being achieved when said drivingclutch element is axially extended relative to said shaft and saidsecond sleeve is advanced axially into said first sleeve; an internalconical face on said driving clutch portion, a pilot extension on saidshaft lying within said conical face, and a ball lock assembly disposedbetween said conical face and said pilot non-retractably locking saidfirst clutch element relative to said shaft in its extended position;said ball lock body being movable to release position to allow axialretraction of said clutch element.

14. A limited torque imparting device comprising a driving clutchelement, a driven clutch element; at least one said clutch element beingadapted to be moved out of engagement relative to said other clutchelement; a torque-wise preloaded final drive spring connected to onesaid clutch element adapted to relatively immovably drive until itspreloaded condition is exceeded and then to move relatively to saidclutch elements, a cam adapted to be activated to disengage said clutchelements by said springs relative movement, a clutch position lockcomprising an axially relatively fixed primary drive shaft, an axiallyextending pilot portion on said drive shaft, a driving clutch portionaxially movably disposed on said drive shaft and slidably keyed theretofor rotation therewith having an internal conical face in the area ofsaid drive shaft pilot portion, a ball lock body having at least onelocking ball disposed between said shaft pilot portion and said drivingclutch portion, and a spring urging said lock body balls into lockingengagement with said clutch portion conical face and said portion so asto lock said clutch portion against movement up said shaft until saidbody first is moved in that direction out of locked condition.

15. A limited torque imparting device comprising a driving clutchelement, a driven clutch element; at least one said clutch element beingadapted to be moved out of engagement relative to said other clutchelement; a torque-wise preloaded final drive spring connected to onesaid clutch element adapted to relatively immovably drive until itspreloaded condition is exceeded and then to move relatively to saidclutch elements, a cam adapted to be activated to disengage said clutchelements by said springs relative movement, a clutch position releasablelock comprising a drive shaft, a lock body having plungers surrounding aportion of said shaft, a clutch portion keyed to said shaft for rotationtherewith and relative axial movement relative thereto having a conicalface portion in the area of said lock body adapted to wedge the plungersof said lock body between itself and said shaft, and a spring urgingsaid lock body into plunger wedging relationship to said face and saidshaft so that said lock body is releasable for axial movement by thrustin one direction and said clutch portion is releasable for axialmovement by thrust in the opposite direction.

16. A limited torque imparting device comprising a driving clutchelement, a driven clutch element; at least one said clutch element beingadapted to be moved out of engagement relative to said other clutchelement; a torquewise preloaded final drive spring connected to one saidclutch element adapted to relatively immovably drive until its preloadedcondition is exceeded and then to move relatively to said clutchelements, a cam adapted to be activated to disengage said clutchelements by said springs relative movement, a clutch position releasablelock comprising a drive shaft, a lock body having plungers surrounding aportion of said shaft, a clutch portion keyed to said shaft for rotationtherewith and relative axial movement relative thereto having a conicalface portion in the area of said lock body adapted to Wedge the plungersof said lock body between itself and said shaft, and a spring urgingsaid lock body into plunger wedging relationship to said face and saidshaft so that said lock body is releasable for axial movement by thrustin one direction and said clutch portion is releasable for axialmovement by thrust in the opposite direction, and friction elementsdisposed between said clutch element and said shaft preventingaccidental movement of said clutch element in the direction of lockrelease.

References Cited in the file of this patent UNITED STATES PATENTS PreeceApr. 20, Wilson et a1. Mar. 7, Schneider Nov. 6, Borchert Aug. 20, PottAug. 27, Tatter Nov. 17, Wengel et a1 Mar. 28,

FOREIGN PATENTS France Jan. 24,

